Robert Helmer MacArthur | |
|---|---|
 | |
| Born | (1930-04-07)April 7, 1930 |
| Died | November 1, 1972(1972-11-01) (aged 42) |
| Alma mater | Marlboro College (BA) Brown University (AM) Yale University (PhD) |
| Known for | Island biogeographyOptimal foraging theory |
| Spouse | Elizabeth Bayles Whittemore |
| Children | 4 |
| Awards | National Academy of Sciences (1969) |
| Scientific career | |
| Fields | |
| Institutions | |
| Thesis | Population Ecology of Some Warblers of Northeastern Coniferous Forests (1957) |
| Doctoral advisor | G. Evelyn Hutchinson |
| Other academic advisors | David Lack |
Robert Helmer MacArthur (April 7, 1930 – November 1, 1972) was a Canadian-born Americanecologist who made a major impact on many areas ofcommunity andpopulation ecology. He is considered to be one of the founders of ecology.[1]
MacArthur was born in Toronto, Ontario, to John Wood MacArthur and Olive Turner in 1930. He later moved toMarlboro, Vermont, as his father moved from theUniversity of Toronto toMarlboro College.[2][3] MacArthur received his Bachelor's degree in mathematics fromMarlboro College, followed by a Master's degree in mathematics fromBrown University in 1953.[3] A student ofG. Evelyn Hutchinson, MacArthur earned his Ph.D. fromYale University in 1957; his thesis was on the division ofecological niches among five warbler species in the conifer forests of Maine and Vermont.[4] From 1957 to 1958, MacArthur worked as apostdoc withDavid Lack.[4]
MacArthur was a professor at theUniversity of Pennsylvania, 1958–65, and professor of biology atPrinceton University, 1965–72. He played an important role in the development ofniche partitioning, and withE.O. Wilson he co-authoredThe Theory of Island Biogeography (1967), a work which changed the field ofbiogeography, drovecommunity ecology and led to the development of modernlandscape ecology. His emphasis onhypothesis testing helped change ecology from a primarily descriptive field into an experimental field, and drove the development oftheoretical ecology.[5][6][1]
At Princeton, MacArthur served as the general editor of the series Monographs in Population Biology, and helped to found the journalTheoretical Population Biology.[7] He also wroteGeographical Ecology: Patterns in the Distribution of Species (1972), which summarizes much of his life's work.[1] He was elected to theNational Academy of Sciences in 1969. Robert MacArthur died ofrenal cancer in 1972.[8]
Robert MacArthur, in collaboration with Edward O. Wilson, developed the influentialtheory of island biogeography, which revolutionized how ecologists understand species diversity and distribution. Their seminal 1967 book,The Theory of Island Biogeography,[9] introduced the concept of a dynamic equilibrium between immigration and extinction rates as determinants of species richness on islands. They also coined ther- and K-selection theory, which describes contrasting reproductive strategies:r-selected species maximize growth rates in unpredictable environments, whileK-selected species emphasize efficiency and competition in stable environments.
Their equilibrium theory has been extensively tested and generally supported by empirical studies. For instance, researchers have validated the predictions regarding the effects of island size and isolation on species diversity through observations in archipelagos like theGalápagos and experimental work onmangrove islands.[10] The theory also laid the foundation formetapopulation andlandscape ecology, broadening its influence far beyond island studies.
In their 1967 paper, MacArthur and Richard Levins formalized the concept oflimiting similarity, showing mathematically that there is an upper limit to how similar coexisting species can be in their resource use.[11] This work provided a theoretical foundation for understanding the conditions under which species with overlapping niches can coexist.
Earlier, MacArthur had demonstrated niche partitioning empirically in his groundbreaking 1958 paper onwarblers (Dendroica species) in northeastern forests.[12] By observing how different warbler species foraged at varying heights and parts of trees, he provided one of the first clear examples of howniche differentiation allows species to coexist.
MacArthur also contributed to the theory ofspecies abundance distributions with his “broken stick model,” first proposed in 1957.[13] This model likens the division of resources in an ecosystem to breaking a stick into randomly sized pieces, predicting the relative abundance of species in a community. While later models (e.g., the log-normal distribution) gained prominence, the broken stick model remains a landmark in the history of ecological theory.
MacArthur was a pioneer in developing mathematical models for consumer-resource dynamics, aiming to explain how interactions between species shapeecological communities. He introduced a general framework for consumer-resource interactions, which is widely used by theoretical modelers today and forms the basis ofmodern coexistence theory.[14] He also used his model to demonstrate that increasing the number of species reduces a community's stability, a precursor to debates on the “diversity-stability” hypothesis.[15]
One of his key contributions was identifying a minimization principle for consumer-resource dynamics. He showed that these systems tend to minimize a quantity related to resource overlap, providing a theoretical foundation for understanding competitive exclusion and coexistence.[16]
In collaboration withMichael Rosenzweig, MacArthur helped develop theRosenzweig-MacArthur model in the early 1960s.[17] Thispredator-prey model incorporates atype II functional response, where the predator’s consumption rate saturates with increasing prey density. Their model is notable for predictingpopulation cycles in predator-prey interactions, which occur due to the lag between prey growth and predator consumption. This work remains central to the study of ecological dynamics.
